1. Field of the Invention
This invention relates to processes and apparatuses for removing agglomerated particles from a fluid stream. In another aspect, the invention concerns removing agglomerates from a solid-containing stream withdrawn from a fluidized bed regenerator.
2. Description of the Related Art
In processes employing a plurality of fluidized solid catalyst and/or sorbent particles (i.e., a fluidized bed process), two or more of the particles may become chemically and/or physically fused together during operation. These agglomerated particles (i.e., agglomerates) can plug downstream process piping and equipment, resulting in a number of operational problems and contributing to increased operation expenses.
Several factors contribute to the formation of agglomerates in a fluidized bed process. One of the most common causes of particle agglomeration is the presence of water, which can enter the process in a number of ways. For example, water may be liberated from fresh catalyst or sorbent particles added to the system, particularly if the particles are at least partially hygroscopic. Water can enter the system through piping and equipment leaks, such as, for example, leaks from steam- or water-cooled vessels or exchangers. Depending on the reaction(s) occurring in the process, water may be the result of a main or side chemical reaction and may actually be synthesized within the system. When coupled with additional contributing factors, such as, for example high temperatures and high pressures, the rate of water-initiated agglomerate formation can be accelerated even further.
One proposed solution for removing agglomerates from a solids-containing stream in a fluidized bed process involves the use of an in-line filter (i.e., screen) that captures and retains the agglomerates, while allowing the fluid stream to pass therethrough. In order to remove the trapped agglomerates, the process is shut down in order to disconnect the surrounding piping and remove the filter so that the agglomerates can be manually removed from the screen. Because this proposed solution requires the process to be shut down and the process piping to be disassembled, this solution is labor-intensive, time-consuming, and relatively expensive. In addition, the screens used in the filters are often fragile and susceptible to damage, thereby rendering the filter ineffective. However, the use of a more robust screen often results in a higher frequency of clogging, which results in more required cleanings, thereby increasing the number of process interruptions.